Photovoltaics, or PV for short, is a Solar Power technology that uses Solar Photvoltaics systems' or Solar cells to provide electricity for human activities. Photovoltaics is also the field of study relating to this technology.

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Monday, November 21, 2011

As fire calls go, this one on a cold January night earlier this year was most unusual for Villas Fire Chief Richard Harron Jr.

Stiff winds were causing a Bay Drive windmill to spin out of control. The brake failed and the turbine was sending large amounts of electricity into connections in the homeowner’s garage. If there was an off switch somewhere, Harron didn’t know where it was. Even after an electrical panel was pulled on the 10-kilowatt windmill, the system was still creating electricity. The windmill company had to be called to come and cut the connections.

“The emergency disconnect actually failed. It didn’t work. It caused an electrical surge and fire in the electrical components in the garage,” Harron said.

Since then Harron has made sure his firefighters have training in dealing with alternative energy systems including wind turbines and solar panel arrays.

It’s a side to alternative energy the public doesn’t hear much about. Such systems create electricity. Even if power is turned off to the home, and incident commanders at fires typically have dispatchers call the electric company to do this right away, solar panels and windmills keep churning out energy as long as the sun is shining and the wind is blowing.

This can cause fires and be a danger to those responding. Harron said it isn’t just firefighters in danger but also police officers, EMTs and others at the scene.

One problem is a lot of new technology is coming out and there seems to be as many differences as similarities.

“Every system is different. One company says it can never happen. Another says it could happen. They all should have electrical shut-offs. They should be on all solar and windmill systems,” Harron said.

Shutting off the system may not be enough. A solar panel system is still charged with energy between the panels and the electrical connections. It can cause a potentially dangerous shock.

A typical residential solar panel system has a maximum of 600 volts. This is considered a low-voltage threat, but nationwide nearly 300 workers a year die from such low voltage electrical incidents, according to the New Jersey Department of Community Affairs’ Division of Fire Safety.

“The one problem is you can’t shut these things off. If there is light, there will be power,” said acting Director Bill Kramer of the Division of Fire Safety.

Kramer, a firefighter for 38 years, said firefighters must treat alternative energy systems as they would other systems.

“The bottom line is we have to treat them like any other live electric, because they are. We deal with live electric every day. I don’t think it’s anything we should be scared of,” Kramer said.

The division has created a PowerPoint training program that is available to fire companies.

Kramer said the division is working to create building codes to alert firefighters to alternative energy systems in their towns. This would allow firefighters to do something called a pre-plan, in which they study a property in advance and have details on any features relevant to fighting a fire.

“We’d like to develop a mechanism where a (construction) permit is pulled and the Fire Service is notified. They can make contact with the installer and pre-plan that system,” Kramer said.

A pre-plan for a solar array on the roof of a house could be important. Firefighters often ventilate smoke from a fire by cutting a hole in the roof, so they need to know in advance where panels are.

Firefighters can’t cut off energy being collected by the panels, but there usually is a way to stop it somewhere between the panels and the electric meter.

Kramer said there have been some solar systems that have failed and caused a fire, and the division is still investigating the Bay Drive windmill incident, but the main worry is not the systems causing the fire. The main worry is firefighters arriving to fight a structure fire and having to work around a fully charged alternative energy system.

A typical system

As long as the sun is out, solar panels are hot. The sunlight excites electrons on the panels and knocks them loose. Conductors capture them and create an electric current.

The DCA even warns that spotlights at night can create electrical current in the panels. It warns firefighters that covering the panels with tarps may not be enough to shut them down.

“Treat all systems as energized regardless of the time of day,” advises the DCA PowerPoint presentation.

If a panel breaks, all the electricity in the system can be released at the break point.

But the systems typically have some shut-offs. The panels create DC, or direct current, and there is often a DC disconnect box. This current is funneled to an inverter that converts the DC to AC, or alternating current. There is often an AC shut-off as well. Connections before the shut-offs would still be hot.

“There are no state laws that say they have to identify where the shut-offs are. Nothing is pre-labeled. It’s on us and on the homeowner,” said Harron.

After the inverter there is a breaker panel that can send AC power to the house, with the excess going to a meter and then the region’s power grid.

A windmill also sends power to an inverter and presents similar dangers to firefighters such as shock, ventricular fibrillation, thermal injury, and, if the equipment catches fire, inhalation issues.

The weight of the systems is another issue. A 40-panel solar array adds 1,400 pounds to the load on the roof. New technology is even using roof or siding shingles as photovoltaic solar cells.

Cape May Fire Chief Jerry Inderwies would like to see a symbol developed alerting responders to such systems, similar to the triangle symbols used to warn about truss roof and floor construction.

“It would be nice if the building was marked, if that was the code. If there’s a snowstorm and the roof is covered, you might not see it,” Inderwies said.

He also would like to learn more about shut-off switches, and hopes the homeowner will at least learn where they are. His department is taking a class on solar systems later this month.

“We’re aware of it. I’ve handed out a lot of literature to my personnel from the Internet. It’s cropping up, and we have to deal with it,” Inderwies said.

A solar state

There are only a handful of wind turbines in the region, but solar arrays are being built at such a rate that New Jersey recently passed California as the No. 1 state for the type of solar panels that create electricity, photovoltaic systems. New Jersey has 24 percent of the nation’s photovoltaic panels, according to the Solar Energy Industries Association, with 11,245 systems generating more than 430 megawatts of power.

Many are large commercial projects spurred by federal tax credits, state incentives including no sales tax, and payments made mostly by utility companies that burn fossil fuels.

Bigger projects may be more important to pre-plan. The Lower Township Municipal Utilities Authority is about to activate a 1.3-megawatt solar field, featuring 5,473 panels covering seven acres of ground at the Bayshore Road plant, in Harron’s fire district.

“We’re going to train on that. The MUA is going to assist us with the training,” Harron said.

Authority Executive Director Matthew Ecker said the solar system takes conventional electric energy to power the equipment that converts DC current to AC current. In a power outage, Ecker said this equipment would not operate and there would be no electricity from the panels going to the utility or the power grid.

“Energy is collected but not transferred. It’s stored,” Ecker said.

Harron is still worried about all that power being there when firefighters arrive.

“It’s like the hybrid cars. Its new technology all the fire departments have to overcome,” Harron said.

Feds getting involved

The National Fire Protection Association has a task force looking into changes to the electrical code to protect first responders. It could result in a standard way to shut down the energy leaving the system. The NFPA’s Mark Earley said the code requires shut-offs, but they are not the same for all systems.

“First responders are looking for an easy way, a rapid way, to disconnect. They need the installers to make a system to easily do these kinds of things,” said Earley.

Still, he noted solar systems are still energized at the panels even if this energy is not being distributed.

Underwriters Laboratories, a private nonprofit organization that tests and certifies products, has been studying the problems under a Department of Homeland Security grant.

“An on-line training program for firefighters should be complete next month. We work with fire departments,” said the UL’s Fire Protection Engineer Robert Backstrom.